Furnace



Jan,t 3, 1928. 1,655,110

E. STEINHORST ET AL.

FURNACE Filed Feb. 27, 1925 2 Sheets-Sheet l vwanozs W ,JL/MM Il* 3,1, www

m 8k W attori/w13 5 Jan. 3, 1928. 1,655,110

E. sTElNHoRsT ET AL FURNACE Filed Feb. 27, 1926 2 Sheets-Sheet 2 attorney S Patented Jan. 3, 1928.

UNITED STATES 1,655,110l PATENT OFFICE.

EMIL STEINEORST AND WILLIAM C. STEINHORST, OF UTICA, NEW YORK, ASSIGN Y TO. EMIL STEINHORST & SONS, INC., OF UTICA, NEW YORK.

FUaNAcE.

Application filed February 27, 1923. Serial No. 91,143.

Our present invention relates to furnaces for warming air and designed particularly to use gas or liquid fuels.

The purpose of our invention is to provide a warm air furnace especially adapted to use fluid fuels, that is either gas or liquid fuel with convenience, safety and efficiency.

A further purpose is to provide a furnace of the type mentioned of such construction,

1o arrangement and combination of its parts that the furnace will be adapted to utilize the heat Afrom the fuel consumed to the greatest possible advantage; adapted to resist the. rusting or corrosive action which l5 tends .to take place due to the presence of moisture andparticularly sulphurous acid within the heater upon condensation of the ases and especially to provide for such conensation to take place where it will do no 2o harm to the heater and where the condensation can be removed from the gases before they pass into the chimney.

.Another object of our invention is to rovide a heater of the type indicated W ere the parts with which the gases of combustion Icome into contact are made of relativel thin light-weight moisture-resisting an acid-resisting material and with said material preferably sheet metal or tubing, said sheet metal and' tubin further preferably being of copper. This lightness of struct-ure enables the whole furnace and in many cases even thelouter casing thereof to be cornpletely assembled in the factory or shop and transported bodily to the basement where it is available for immediate operation upon making the connections for the fluid fuel,

incoming cold air, outgoin warm air and smoke pipe and condensation drain."

Another advantage of the light weight of our heater is that it begins to give an a'p preciable sup ly of warm air practically at the instant of) going into operation for the reason that the furnace does not .have the usualmass or thickness of metal to be heated before the air passing therethrough is heated. This substantially instantaneous heating operates not only when the furnace is first put into operation but at each time when t e thermostatic automatic control turns n the fuel. The fact that the combustion chamber, lines and gathering or condensation chamber of the furnace. are of sheet metal or tubing and preferably sheet copper or copper tubing results in the device getting a very large percentage of the heat rom the products of combustion into the air-being warmed on the other side of this thin metal andy where copper is used any especially highly heated art of the metal will transfer its heat rapid y and to a great dis tance through the copper so that'said heat may be absorbed by the air at other points. The ossibility of making a warm air heater of this light weight construction and getting the great advantages thereof results from appreciating that a furnace designed exclusively to use fluid fuel does not have-to follow the excessively heavy construction that has always been used with solid fuel and used heretofore, as far as we are aware, even with fluid fuel.

Still further purposes of our invention are to provide a furnace of the class described vvhere many iues or pipes are used '15 to pass the gases through and these lues are arranged so that there is a very ready and extensive circulation of air past said ilues; and further preferably to have said flue pipes of a special type of construction in order to radiate the heat from said ilues into the surrounding part by means of fins or lianges projecting from said pipes at closely spaced intervals.

Fig. 1 is a view looking at the front of a furnace embodying our invention, said view being partly a front elevation, partly a vertical sectional view just within the front of the casing and partly a vertical sectional view through the upper right hand portion of the combustion chamber.

Figi. 2 is a view mostly in longitudinal central section through the furnace with the rear portion of the combustion chamber and that part of the flues and all of the gathering chamber shown in side elevation. Y

' Fig. 3 is a detailed sectional view on an enlarged scale illustrating theform of the ues and their connection to the chambers Referring to the drawings in a more particular description it will be seen that our furnace comprises a combustion4 chamber 10,

burners 11 therein, a large number of iues 12 leading from the upper Dart of said combustion chamber downwardly preferably on both sides thereof to the gathering and condensation chamber 13 spacedV below the combustion chamber;

From the base 14 there extend upwardly four uprights 15 conveniently formed of 110 angle iron andA locatedat the four corners of the combustion chamber 10. Between the forward pair of these uprights and rigidly secured thereto is an inverted V-shaped stirrup or bracket 16 and a similar bracket is located between the two rear uprights 15. Upon these two brackets rests the combustion chamber 10 with the angles of the uprights 15 enclosing the four corners of the greater part of said combustion chamber. Near their upper ends the front air of uprights and the rear pair of uprig its are connected by transversely extending cross bars 17 which cross bars extend beyond the combustion chamber and beyond the iues 12 to the casing 18. The opposite ends of each cross bar are turned at a right angle to the length of the cross bar forming convenient means to locate and brace the casing at the two sides thereof near the front and rear ends of the furnace. Just outside the combustion chamber the front and rear cross bars 17 are tied together by longitudinal strips 19. The combustion chamber 10 is somewhat irregular in shape but preferably is so formed as to be rectangular in cross section at any plane. The main portion of the combustion chamber it will be seen is a plain rectangular box but its bottom is V-shaped with the bottom walls 20 sloping downwardly to each other as appears in Fig. 1 with the front edges of-these walls resting upon the V-shaped brackets 16. The upper part of the combustion chamber as seen in transverse section is roughly shaped like an hour-glass in that the side walls of said combustion chamber rst slope towards each other as at 21 as they extend -upwardly and then extend directly upwardly as at 22 forming a neck portion of reduced size and then the side walls again flare outwardly as they continue upwardly as at the surfaces 23. Above the slanting portions 23 the side walls extend directly upward for a very short distance to meet the flat top 24.

In the front end of the combustion chamber there is provided a door aperture 25 through which are placed into the combustion chamber the burners 11 and through which also is admitted the air to support combustion when the furnace is in operation. As shown in the drawings this aperture is provided with a forwardly extending flange 27 extending to or just through the casing at the front of the furnace to form a passage-way leading from without the furnace to the inside of the combustion chamber. To the outer end of this flange 27 is secured the cgrrespondingly five-sided door frame 28 upon which is hinged the door 31.

About midway the height of this door frame the door 31 ceases but has hinged thereto the air door 62. The door 31 is provided with a panel 30 of transparent materialas mica or the like so that the operator may see the condition of the ame at the burners. The door 62 has an outwardly extending ear 32 to which may beattached the chain 33 to control as hereinafter mentioned the extent to which the dobr is opened. The particular type of the fluid fuel burner is no part of our invention. We have illustrated our furnace as using an aproved form of gas burner 11. As indicated in the drawings eight such burners are usually arranged in two rows of four burners each extending longitudinally, that is from front to rear of the combustion chamber. The different burners in each row are connected by short lengths of pipe 34 which provide passage ways for the fuel between adjacent burners. In the system of burners illustrated in the drawings gas is separately supplied to each row of burners through pipe 35 connected to the front end of the front burner. This pipe 35 extends forwardly part way through the passage formed by the fiange 27 and then turns laterally through the side portions of the said flange to the horizontal runsv of pipe 36. The pipes 36 from the opposite rows of burners extend laterally from the opposite side portions of the flange 27 just within the front of the casing 13 and then extend through the sides of said casing. From this point pipes 37 extend forwardly and upwardly to a line outside ofthe front casing and at a level above the door frame and then horizontal runs of pipe 38 bring the supply lines to a common inverted T 39. To the third orlarger end of this T is connected the main single supply pipe 40. In this supply pipe 40 preferabl at a point just above the front door of t e furnace is provided a quick-acting valve 41 with a forwardly extending lever 42. To this valve lever 42 is connected the chain v33 coming up from the air supply door 31 with said chain operated as required by a motor (not shown) which motor 1s thermostatieally controlled. It will be obvious o-f course that our furnace could be used without thermostatic control, that is the supply of gas and air could be manually regulated as needed but for ordinary purposes the thermostatic control is advantageous in order to get the proper even temperature desired with as small a consumption of fuel as possible.

The burners 11 are supported at the proper elevation within the combustion chamber by two or more of the burners in each row being rested upon the top cross bar 43 of a triangular support formed from said cross bar 43 and converging side pieces 44 which side pieces 44 rest against the convergino'lbottom portions 20 of the combustion chamber. The two or more of these triangular supports that are used are permanently connected and held upright by .connecting strips 45. A horizontal late 46 Vclosely enough to each other and to the adjacent walls of the combustion chamber to allow onl the proper amount of air to go up past tlie burners as distinct from the air that is drawn up into the burners.

The gathering or condensation chamber 13 already mentioned/as being spaced below the combustion chamber is generally of the shape of a long square box arranged at an angle so that it has two upper sides 48 and 49 meeting at an angle of ninety degrees and two lower sides 50 and 51. T e lower angle of this long box, however, is cut off by a flat bottom 47 which slopes downwardly as it extends from the front of "the condensation chamber to the rear thereof in order to provide for a positive flow of the moisture of condensation within this chamber to the drain pipe 52. It will be understood that the front of this condensation chamber is closed as by front end 53 but that the rear end of this chamber projects outwardly through the outer casing 18 and thereafter is shaped into circular'form to connect with the large pipe 54 which extends upwardly to the chimney. The drain pipe 52 is connected to the lowest point of the condensation chamber just outside the casing 18.

Preferably as already suggested the combustion chamber 10 and the condensation chamber 13 will be constructed of sheet metal and preferably this sheet metal will be of such material as to withstand the moisture and the sulphurous acid present in said moisture when condensation takes place as the gases of combustion are cooled to a relatively low temperature. Preferably as such moisture and acid-resisting material we use copper as said material has the added advanta e of being a good conductor `of heat.

rom the upper part of the combustion chamber, that is from the sloping sides 23 thereof to the upper and sloping sides 48 and 49 of the combustion chamber 13 there extend the iues 12. As will be seen from the drawings there are a great number of these flues arranged on both sides of the combustion chamber and preferably arranged in more then one row or series of tlues on each side of the combustion chamber. Inl practice we use as shown in Fig. 1 two rows of such iues on each side of the combustion chamber as this combines the necessary number of iues and convenience of manufacture and assembling thereof with a very general or extensive circulation of the air between the ilues on each side of the combustion chamber. The flues of both the inner and outer rows extend downwardly and outwardly as at 12b from the sloping portion 23 of thel side wall of the combustion chainber to a point about on a level with the cross bars 17. From here the flues extend downwardly to about the level of the burners and referably in this central portion 12n the ues slant slightly inward. The lower portion 12c of each flue then slants sharply inward to its upper side 48 or 49 of the condensation chamber 13.

-These flues 12 are preferably formed of copper pipe and wlth the pipe of relatively small diameter, for example about threequarters of an inch in diameter so that all parts of the current of gases of combustion maybe close enough to a radiating surface to cgive up its heat. To further increase the ra lation from these iues 12 they are preferabl formed with tins or a continuous spira lin 55 projecting outward radially from the pipe. v

As indicated in the drawing this lin 55 on each flue 12 begins as close to the ends of the flue as is practicable for assembling purposes and extends the whole length of the flue. The ends of the ues ma be attached in any convenient way to t e sheet metal of the gathering chamber and to the sheet metal of the combustion chamber. Preferably such fastening will be effected by forming upon the flue a short distance from its end an encircling outwardl -projecting rib 56 which will bear against the outer surface of said sheet metal with the end of the pipe extended through a suitable sized aperture in the said sheet metal and then, turned back from the hole on the inside of the sheet metal as flanve 57 which construction forms a joint which is strong mechanically and gas-tight.

. Near the bottom of the casing 18 are pro vided apertures for the connection to the furnace of the usual incoming cold air conv duits 58.. In the top of the casing are lprovided the necessar number of openings to which are attache the usualconduits 59 to conduct the warm air from the top of the w furnace.

.y -On top of the combustion chamber there extending from the combustion chamber through the outer casing with la door frame 'and air supply door 62 on the main door 3l lill) los the same as at the front of the furnace.' `This air supply door 62 is also connected by chain 63 to the same motor or other raising means as is the chain 33 for the front door. In this way the air supply for the burners is introduced at both ends of the furnace tending to equalize the combustion at the burners. It will be understood that this additional air supply at the rear end of the furnace is not an absolute essential to the furnace, but is we believe the preferred modi- Iication to further aid in procuring most ellicient combustion of the fuel.

Our construction of furnace is peculiarly adapted to be enlarged to produce larger sizes of furnaces as may be re uired for larger houses or buildings. Suc ment is obtained by lengthening the combustion chamber, gathering chamber and of course the casin and adding proportionately more llues and y inserting in the enlarged combustion chamber one or more additional fluid-fuel burners. It will be noticed that this enlargement of the furnace is entirely in addin to its length and to the parts in the length of lthe furnace, but that the transverse construction of the furnace is not changed. This is an advantage` from the manufacturing standpoint as the same sizes of parts can be used for the front and rear casings, the front and rear of the combustion chamber and the front and rear doors and also especially the two sizes and lengths of iiue can be used for any such length of furnace. Of course for much larger sizes of furnaces the whole dimensions both transversely and in height may be increased but this is not necessa? for the ordinary range of sizes required or the usual houses and other buildmgs. f

As already suggested, the flow of the gases resulting from combustion at the burners will be from the burners up through the combustion chamber to the enlarged upper portion thereof; then laterally to its opposite sides and to and through the great number of iiues 12. Through these flues the travel of these hot gases will be downwardly for a relativel long distance in proportion to the size of the furnace, that is to the common gathering or condensation chamber 13 located below the combustion chamber. The direction of travel of the air being warmed is directly contary or reverse to the travel of the gases in the flues 12. In other words, the air coming back from the house to be warmed through the cold airiinlets 58 is at once diverted upwardly by the condensation chamber 13 and then travels upwardly surrounding the flues 12. In this upwardv travel of the air it passes between the closely aced flues .and A1s especially effective in a sorbing the heat from the flues because the air not only asses upwardly along the fines but most o the air has to pass from enlargeoutside the iues to the inside of the ues tol the space 65 about two-thirds of the way up upon the combustion chamber due to the said flues even in their middle portion slanting outwardly to a point very close to the casing 18. The movement of the air into this portion is also accelerated by reason of this portion of the combustion chamber being very hot and so very rapidly heating the air in contact therewith. From the space 65 the air again travels upwardly and then outwardly through the upper sloping portions 12b of the ues. In all of this travel of the air past the flues the fins on said iiues help to break up and thoroughly distribute the traveling air and at the same time impart the heat from the flues to the air. It will be seen, therefore, that in the upward travel of the air past the combustion chamber most of the air will have been twice passed through the spaces between both rows of flues on either side of the furnace. This additional contact or travel of air is very helpful in getting a complete and rapid heating of the air. It will be noticed also that the incomin cold air from the air inlets 58 is rst broug t into contact with the lower end. of the ilues where the gases of combustion have been most condensed and cooled off and that as the air ascends it will be successively brought into contact with warmer portions of the flues until as p the air gets to the top of the iiues and to the top of the combustion chamber the air is in contact with the hottest portion of the furnace. The cooling of the gases of combustion by the heat being abstracted therefrom by the air is so marked in our furnace that when the gases of combustion leave the condensation chamber 13 they are at a temperature of about 110 Fahr.

With the gases of combustion condensed to'this low temperature it will be obvious that a great'deal of moisture will be present in the lower ortion of the flues and particularly in t e condensation chamber 13. This sharp condensation of the gases of combustion helps greatly toward inducing the downward travel of the gases through the flues 12 in that the gases are being cooled as they travel down through said flues. This moisture gathering in the lower portion of the iues runs down the iiues into the condensation chamber and this moisture and further moisture condensing in the condensation chamber 13 runs down the slanting bottom of the condensation chamber to the drain pipe 52 as also does some condensation occurring in pipe 54. In this way substantially all moisture is removed from the gases of combustion before they are conducted into the chimney, and what little moisture remains in the gases is absorbed by the very considerable quantity of air mixed with the gases at this last stage either all through the usual check draft in the socalled smoke pipe or through an additional opening provided in the chimney which opening is left open at all times.

The extremely low temperature of the gases of combustion at the end of the travel of the gases through the. iues or at what 1s commonly called stack temperature, which temperature as mentioned tests a-s low as 110 Fahr., indicates of course that the heat hasgbeen taken from the gases to the air beingwarmed to a much greater extent than heretofore. In many furnaces burning solid and in most furnaces burning fluid-fuel this temperature of the gases -at the vent outlet is from 300 to 500 degrees Fahr. or even several hundred degrees higher. This escape of the gases at such a high temperature is wasteful of fuel and more so when the higher priced fuels as oil and especially gas are being used. Such high temperature at the vent to the stack has heretofore been thought necessary and in fact was necessary where iron or steel parts were used for the furnace This high vent or stack temperature took away the gases before any considerable condensation thereof into moisture took place, An appreciable condensation into water with sulphurous acid present would soon rust or eat away the iron or steel of the furnace and so was to be avoided even though involving what was thought to be merely a theoretical or at least an unavoidable waste of fuel. By making Aour combustion chamber, flue pipes and gathering chamber of copper or other acid-resisting and rust-resistin material, we have produced a furnace wiere such condensation is not harmful and therefore a furnace where condensation can be carried as far as possible and so fuel saved that has heretofore been wasted.

The use of copper or other acid-resisting material and the especially eiicient construction of our furnace in other respects has enabled us to produce a furnace that uses either oil or gas fuels eiiiciently enough to be active competitors with solid fuel furnaces notwithstanding the greater relative cost of the oil and especially the manufactured gases.

It will be understood of course that exact parity of cost of fuel is not necessary to allow oil and especially gas burning furnaces to compete with furnaces using solid fuels. The gas burning furnaces entirely eliminate the trouble, dirt and expense of getting the fuel into the cellar, and putting it into the furnace, then removing the ashes daily from the furnace and periodically from the cellar.

Uur gas burning furnace withthermostatic-control is especially convenient and efficient in fuel consumption because of its being able to be started instantaneously the thermostatic control has moved the lever of the gas valve 4l to closed position. Preferably this is accomplished by providing a hole 64 in the disk 65 of the said valve. It will thus be seen that even though the disk of the valve has been closed a small amount of gas will passthrough the valve. This hole is purposely made of such size that enough gas will be admitted to keep all of the burners lighted with about as small a llame as can be safel used This rovides a small amount o heat and ena les all of the burners to light at once to full capacity when the .valve 4l is a ain turned on. With this arrangement t e furnace may be lit in the fall and can remain in operation until it is turned olf the next spring.

What we claim as new and desire to secure by Letters Patent is:

1. In a warm-air furnace, the combination of a sheet copper combustion chamber, fluidfuel burners in the lower part of the combustion chamber, a plurality of iues leading from the upper part of the combustion chamber, a gathering chamber to which the Hues are connected, a vent pipe leading from the gathering chamber to the chimney, a drain pi e leading from the lower part of the gatherlng chamber, a casing surrounding said combustion chamber, gathering chamber and flues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

2. In a warm-air furnace, the combination of a' sheet copper combustion chamber, fluid-fuel burners in the lower part of the combustion chamber, a plurality of copper flues leading from the upper part of the combustion chamber, a gathering chamber lto which the ues are connected, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of thev gatherin chamber, a casing surrounding said com ustion chamber, gathering chamber and iiues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace. c

3. In al warm-air furnace, the combination of a copper combustion chamber, fluid-fuel burners in the lower part of the combustion chamber, a plurality of flues leading from the uplper part of the combustion chamber, a gat ering chamber having sheet copper walls to which the flues are connected, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the athering chamber, a casing surrounding said combustion chamber, gathering chamber and ilues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace. y

4. In a warm-air furnace, the combination of a combustion chamber, Huid-fuel burners in the lower part of the combustion chamber, a plurality of copper iiues leading from the upper part of the combustion chamber,

acuario ing surrounding said combustion chamber, gathering chamber and lues, an inlet for cold'air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

8. In a warm-air furnace the combination of a combustion chamber, Huid-fuel burners in the lower part ofthe combustion chamber, a sheet copper gatherin chamber below the level of the burners, a purality of iues leading continuousl -downward from the upper part of the com usti'on chamber to the upper a gathering chamber to which the iues are\part of said gatherin chamber, a vent pipe connected, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustionchamber, gathering cham-` ber and fines, anfinlet for cold air near the base of the casing and means connectedto the upper part of the casing for conducting the warm air from the furnace. f

5. In a warm-air furnace, the combination of a combustion chamber, fluid-fuel burners in the lower part of thecombustion chamber, a plurality of copper i'lues leading from the upper part of the combustion chamber, a copper gathering chamber to which the iiues are connected, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and iues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

6. In a warm-air furnace the combination of a copper combustion chamber, Huid-fuel burners in the lower part of the combustion chamber, a plurality of copper iues lending from the upper part of the combustion chamber, a copper gathering chamber to which the ilues are connected, a vent pi e leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gatherin chamber, a casing surroundin said com ustion chamber, gathering cham er and iiues, an inlet for cold air near the base of the casing and means connected to the upper part of the y casing for conducting the warm air from the furnace.

7 In a warm-air furnace the combination of a combustion chamber, fluid-fuel burners in the lower part of the combustion chamber, a gathering chamber below the level of the burners, a plurali of I'iues leading continuouslv downwar from the upper part of the combustion chamber to the upper part of the said gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casgathering chamber below the level of the urners, a pluralit of lues leading continuously downward rom the upper part of the combustion chamber to the upper part of the said gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and iiues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

10. In a warm-air furnace, the combination of a combustion chamber, fluid-fuel burners in the lower part of the combustion chamber, a gathering chamber below the bottom of the combustion-chamber, a multitude of small, closely spaced flues located on the opposite -sides of the combustion chamber and extending from the upper art of the combustion chamber continuous y down to the upper part of said gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and iiues, an inlet for cold air near the base of the casing and means connected to the upper part bustion chamber and extending from the upper part of the combustion chamber continuously down to the upper part of said vso ` and lues, an inlet for col gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and iues, an inlet for cold air near the base of the casing and means connected .to the upper part of the casing for conducting the Warm air from the furnace.

12. In a warm-air furnace, the combination of a combustion chamber, fluid-fuel burners in the lower part of the combustion chamber, a gathering chamber below the bottom of the combustion chamber, a multitude of small, closely spaced fiues located on the opposite sides of the combustion chamber and extending from the upper part of the combustion chamber continuously down to the upper part of said gathering chamber, a vent pi e leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and iiues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace, said iiues being arranged in a plurality of rows on each side of the combustion chamber and slanting intermediate their ,ends nearly to the casing and then back to the gathering chamber whereby air admitted to the casing has to travel inwardly between laid iues and then outwardly between said ues.

13. -In a Warm-air furnace, the combination of a combustionl chamber compact in cross area, fluid-fuel burners in the lower part of said combustion chamber, a gathering chamber below the combustion chamber, a multitude of relatively small, closely spaced 4tubular iues extending in a slanting direction continuously downwards from the upper portion ofthe combustionchamber to the gatheringl chamber, a vent pipe leading from the gat ering chamber to the chimney, a. drain pipe leading fromthe lower part of the gathermg'chamber, a 'casing surrounding said combustion chamber, (gathering chamber Vair near .the base signatures, this 6th da of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

14. In a warm-air furnace the combination of a combustion chamber compact in cross area, Huid-fuel burners in the lower part of said combustion chamber, a gathering chamber below the combustion chamber, a multitude of small closely spaced tubular iiues provided w-ith circumferentially extending iins, said iiues extending continuously from the upper portion of the combustion chamber downwards to the gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and lues, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace.

15. In a warm-air furnace, the combination of a combustion chamber alike transversely throughout its length, duid-fuel burners in the lower part of said combustion chamber, a gathering chamber alike transversely throughout its length and located below and parallel with the combustion chamber, a multitude of small closely spaced tubular fiues extending from the upper portion of two opposite sides of the combustion chamber downwards to the correspondingly arranged opposite sides of the gathering chamber, a vent pipe leading from the gathering chamber to the chimney, a drain pipe leading from the lower part of the gathering chamber, a casing surrounding said combustion chamber, gathering chamber and fines, an inlet for cold air near the base of the casing and means connected to the upper part of the casing for conducting the warm air from the furnace, different sizes of the furnaces being made by varying the length of the sides of the combustion chamber, of the gathering chamber and of the sides of the casing and the number of iues used and using the saine units for iiues and for ends of the combustion chamber, gatherin chamber and casing.

n witness whereof we have. aixed our of February 1926. EMIL STEI ORST. WILLIAM C. STEINHORST. 

